Silly as it may sound, I'm not sure what 'comfortable' is suppose to be on this backpack leaf blower. There's no 'sweet spot' where the blower feels more or less comfortable, but the problem is that shoulder straps keep slipping off my shoulders. It's as if I need a strap across my chest like the one at my waist. I'm 6'2 and have a 44" chest --- does that mean the straps would theoretically be fully extended?